2 beam.cc -- implement Beam
4 source file of the GNU LilyPond music typesetter
6 (c) 1997--2000 Han-Wen Nienhuys <hanwen@cs.uu.nl>
7 Jan Nieuwenhuizen <janneke@gnu.org>
13 * shorter! (now +- 1000 lines)
15 * move paper vars to scm
17 remove *-hs variables, and do all y-position stuff in staff-space.
21 #include <math.h> // tanh.
23 #include "molecule.hh"
24 #include "directional-element-interface.hh"
28 #include "least-squares.hh"
30 #include "paper-def.hh"
32 #include "group-interface.hh"
33 #include "staff-symbol-referencer.hh"
39 Beam::add_stem (Grob*me, Grob*s)
41 Pointer_group_interface:: add_element(me, "stems", s);
43 s->add_dependency (me);
45 assert (!Stem::beam_l (s));
46 s->set_grob_property ("beam", me->self_scm ());
48 add_bound_item (dynamic_cast<Spanner*> (me), dynamic_cast<Item*> (s));
52 Beam::get_multiplicity (Grob*me)
55 for (SCM s = me->get_grob_property ("stems"); gh_pair_p (s); s = gh_cdr (s))
57 Grob * sc = unsmob_grob (gh_car (s));
59 if (Stem::has_interface (sc))
60 m = m >? Stem::beam_count (sc,LEFT) >? Stem::beam_count (sc,RIGHT);
66 After pre-processing all directions should be set.
67 Several post-processing routines (stem, slur, script) need stem/beam
69 Currenly, this means that beam has set all stem's directions.
70 [Alternatively, stems could set its own directions, according to
71 their beam, during 'final-pre-processing'.]
73 MAKE_SCHEME_CALLBACK(Beam,before_line_breaking,1);
75 Beam::before_line_breaking (SCM smob)
77 Grob * me = unsmob_grob (smob);
81 Why what? Why the warning (beams with less than 2 stems are
82 degenerate beams, should never happen), or why would this ever
83 happen (don't know). */
84 if (visible_stem_count (me) < 2)
86 warning (_ ("beam has less than two stems"));
88 if (visible_stem_count (me) >= 1)
90 if (!Directional_element_interface::get (me))
91 Directional_element_interface::set (me, get_default_dir (me));
93 consider_auto_knees (me);
94 set_stem_directions (me);
95 set_stem_shorten (me);
101 Beam::get_default_dir (Grob*me)
103 Drul_array<int> total;
104 total[UP] = total[DOWN] = 0;
105 Drul_array<int> count;
106 count[UP] = count[DOWN] = 0;
109 Link_array<Item> stems=
110 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
112 for (int i=0; i <stems.size (); i++)
115 Direction sd = Directional_element_interface::get (s);
116 int current = sd ? (1 + d * sd)/2
117 : Stem::get_center_distance (s, (Direction)-d);
125 } while (flip(&d) != DOWN);
127 SCM func = me->get_grob_property ("dir-function");
128 SCM s = gh_call2 (func,
129 gh_cons (gh_int2scm (count[UP]),
130 gh_int2scm (count[DOWN])),
131 gh_cons (gh_int2scm (total[UP]),
132 gh_int2scm (total[DOWN])));
134 if (gh_number_p (s) && gh_scm2int (s))
138 If dir is not determined: get default
140 return to_dir (me->get_grob_property ("default-neutral-direction"));
145 Set all stems with non-forced direction to beam direction.
146 Urg: non-forced should become `without/with unforced' direction,
147 once stem gets cleaned-up.
150 Beam::set_stem_directions (Grob*me)
152 Link_array<Item> stems
153 =Pointer_group_interface__extract_elements (me, (Item*) 0, "stems");
154 Direction d = Directional_element_interface::get (me);
156 for (int i=0; i <stems.size (); i++)
159 SCM force = s->remove_grob_property ("dir-forced");
160 if (!gh_boolean_p (force) || !gh_scm2bool (force))
161 Directional_element_interface ::set (s,d);
166 Simplistic auto-knees; only consider vertical gap between two
169 `Forced' stem directions are ignored. If you don't want auto-knees,
170 don't set, or unset auto-knee-gap.
173 Beam::consider_auto_knees (Grob *me)
175 SCM scm = me->get_grob_property ("auto-knee-gap");
177 if (gh_number_p (scm))
181 Real staff_space = Staff_symbol_referencer::staff_space (me);
182 Real gap = gh_scm2double (scm) / staff_space;
184 Direction d = Directional_element_interface::get (me);
185 Link_array<Item> stems=
186 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
188 Grob *common = me->common_refpoint (stems[0], Y_AXIS);
189 for (int i=1; i < stems.size (); i++)
190 common = common->common_refpoint (stems[i], Y_AXIS);
192 for (int i=1; i < stems.size (); i++)
194 Real left = Stem::extremal_heads (stems[i-1])[d]
195 ->relative_coordinate (common, Y_AXIS);
196 Real right = Stem::extremal_heads (stems[i])[d]
197 ->relative_coordinate (common, Y_AXIS);
199 Real dy = right - left;
203 knee_y = (right + left) / 2;
211 for (int i=0; i < stems.size (); i++)
214 Real y = Stem::extremal_heads (stems[i])[d]
215 ->relative_coordinate (common, Y_AXIS);
217 Directional_element_interface::set (s, y < knee_y ? UP : DOWN);
218 s->set_grob_property ("dir-forced", SCM_BOOL_T);
225 Set stem's shorten property if unset.
227 take some y-position (chord/beam/nearest?) into account
228 scmify forced-fraction
231 Beam::set_stem_shorten (Grob*m)
233 Spanner*me = dynamic_cast<Spanner*> (m);
235 Real forced_fraction = forced_stem_count (me) / visible_stem_count (me);
236 if (forced_fraction < 0.5)
239 int multiplicity = get_multiplicity (me);
241 SCM shorten = me->get_grob_property ("beamed-stem-shorten");
242 if (shorten == SCM_EOL)
245 int sz = scm_ilength (shorten);
247 Real staff_space = Staff_symbol_referencer::staff_space (me);
248 SCM shorten_elt = scm_list_ref (shorten, gh_int2scm (multiplicity <? (sz - 1)));
249 Real shorten_f = gh_scm2double (shorten_elt) * staff_space;
251 /* cute, but who invented me -- how to customise ? */
252 if (forced_fraction < 1)
255 Link_array<Item> stems=
256 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
258 for (int i=0; i < stems.size (); i++)
261 if (Stem::invisible_b (s))
263 if (gh_number_p (s->get_grob_property ("shorten")))
264 s->set_grob_property ("shorten", gh_double2scm (shorten_f));
269 Set elt properties height and y-position if not set.
270 Adjust stem lengths to reach beam.
272 MAKE_SCHEME_CALLBACK(Beam,after_line_breaking,1);
274 Beam::after_line_breaking (SCM smob)
276 Grob * me = unsmob_grob (smob);
278 /* first, calculate y, dy */
280 calc_default_position_and_height (me, &y, &dy);
281 if (visible_stem_count (me))
283 if (suspect_slope_b (me, y, dy))
286 Real damped_dy = calc_slope_damping_f (me, dy);
287 Real quantised_dy = quantise_dy_f (me, damped_dy);
289 y += (dy - quantised_dy) / 2;
293 until here, we used only stem_info, which acts as if dir=up
295 y *= Directional_element_interface::get (me);
296 dy *= Directional_element_interface::get (me);
299 Real half_space = Staff_symbol_referencer::staff_space (me) / 2;
301 /* weird: why do we do calc_position_and_height () ? regardless of
304 If the user sets height, we still need to calculate the y-position.
305 If the user sets height-hs, we still need to calculate and
308 We use least squares to calculate y-position and height, so we
309 inherently always calculate both. */
311 /* check for user-override of dy */
312 SCM s = me->remove_grob_property ("height-hs");
315 dy = gh_scm2double (s) * half_space;
317 me->set_grob_property ("height", gh_double2scm (dy));
319 /* check for user-override of y */
320 s = me->remove_grob_property ("y-position-hs");
323 y = gh_scm2double (s) * half_space;
327 /* we can modify y, so we should quantise y */
328 Real y_shift = check_stem_length_f (me, y, dy);
330 y = quantise_y_f (me,y, dy, 0);
331 set_stem_length (me, y, dy);
332 y_shift = check_stem_length_f (me, y, dy);
334 if (y_shift > half_space / 4)
339 for significantly lengthened or shortened stems,
340 request quanting the other way.
343 if (abs (y_shift) > half_space / 2)
344 quant_dir = sign (y_shift) * Directional_element_interface::get (me);
345 y = quantise_y_f (me, y, dy, quant_dir);
348 // UGH. Y is not in staff position unit?
349 // Ik dacht datwe daar juist van weg wilden?
350 set_stem_length (me, y, dy);
351 me->set_grob_property ("y-position", gh_double2scm (y));
353 return SCM_UNSPECIFIED;
357 See Documentation/tex/fonts.doc
360 Beam::calc_default_position_and_height (Grob*me,Real* y, Real* dy)
364 if (visible_stem_count (me) <= 1)
367 Real first_ideal = Stem::calc_stem_info (first_visible_stem (me)).idealy_f_;
368 if (first_ideal == Stem::calc_stem_info (last_visible_stem (me)).idealy_f_)
375 Array<Offset> ideals;
377 // ugh -> use commonx
378 Real x0 = first_visible_stem (me)->relative_coordinate (0, X_AXIS);
379 Link_array<Item> stems=
380 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
382 for (int i=0; i < stems.size (); i++)
385 if (Stem::invisible_b (s))
387 ideals.push (Offset (s->relative_coordinate (0, X_AXIS) - x0,
388 Stem::calc_stem_info (s).idealy_f_));
391 minimise_least_squares (&dydx, y, ideals); // duh, takes references
393 Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - x0;
398 Beam::suspect_slope_b (Grob*me, Real y, Real dy)
400 /* first, calculate y, dy */
402 steep slope running against lengthened stem is suspect
404 Real first_ideal = Stem::calc_stem_info (first_visible_stem (me)).idealy_f_;
405 Real last_ideal = Stem::calc_stem_info (last_visible_stem (me)).idealy_f_;
406 Real lengthened = gh_scm2double (me->get_grob_property ("outer-stem-length-limit"));
407 Real steep = gh_scm2double (me->get_grob_property ("slope-limit"));
409 // ugh -> use commonx
410 Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - first_visible_stem (me)->relative_coordinate (0, X_AXIS);
411 Real dydx = dy && dx ? dy/dx : 0;
413 if (((y - first_ideal > lengthened) && (dydx > steep))
414 || ((y + dy - last_ideal > lengthened) && (dydx < -steep)))
422 This neat trick is by Werner Lemberg,
423 damped = tanh (slope)
424 corresponds with some tables in [Wanske]
427 Beam::calc_slope_damping_f (Grob*me,Real dy)
429 SCM damp = me->get_grob_property ("damping");
430 int damping = gh_scm2int (damp);
434 // ugh -> use commonx
435 Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS)
436 - first_visible_stem (me)->relative_coordinate (0, X_AXIS);
437 Real dydx = dy && dx ? dy/dx : 0;
438 dydx = 0.6 * tanh (dydx) / damping;
445 Beam::calc_stem_y_f (Grob*me,Item* s, Real y, Real dy)
447 int beam_multiplicity = get_multiplicity (me);
448 int stem_multiplicity = (Stem::flag_i (s) - 2) >? 0;
450 SCM space_proc = me->get_grob_property ("space-function");
451 SCM space = gh_call1 (space_proc, gh_int2scm (beam_multiplicity));
453 Real thick = gh_scm2double (me->get_grob_property ("thickness")) ;
454 Real interbeam_f = gh_scm2double (space) ;
456 // ugh -> use commonx
457 Real x0 = first_visible_stem (me)->relative_coordinate (0, X_AXIS);
458 Real dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - x0;
459 Real stem_y = (dy && dx ? (s->relative_coordinate (0, X_AXIS) - x0) / dx * dy : 0) + y;
462 Direction dir = Directional_element_interface::get (me);
463 Direction sdir = Directional_element_interface::get (s);
469 * (thick / 2 + (beam_multiplicity - 1) * interbeam_f);
473 // huh, why not for first visible?
474 if (Staff_symbol_referencer::staff_symbol_l (s)
475 != Staff_symbol_referencer::staff_symbol_l (last_visible_stem (me)))
476 stem_y += Directional_element_interface::get (me)
477 * (beam_multiplicity - stem_multiplicity) * interbeam_f;
484 Beam::check_stem_length_f (Grob*me,Real y, Real dy)
488 Direction dir = Directional_element_interface::get (me);
490 Link_array<Item> stems=
491 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
493 for (int i=0; i < stems.size(); i++)
496 if (Stem::invisible_b (s))
499 Real stem_y = calc_stem_y_f (me, s, y, dy);
502 Stem_info info = Stem::calc_stem_info (s);
504 // if (0 > info.maxy_f_ - stem_y)
505 shorten = shorten <? info.maxy_f_ - stem_y;
506 // if (0 < info.miny_f_ - stem_y)
507 lengthen = lengthen >? info.miny_f_ - stem_y;
510 if (lengthen && shorten)
511 warning (_ ("weird beam vertical offset"));
513 /* when all stems are too short, normal stems win */
514 return dir * ((shorten) ? shorten : lengthen);
518 Hmm. At this time, beam position and slope are determined. Maybe,
519 stem directions and length should set to relative to the chord's
520 position of the beam. */
522 Beam::set_stem_length (Grob*me,Real y, Real dy)
524 Real half_space = Staff_symbol_referencer::staff_space (me)/2;
525 Link_array<Item> stems=
526 Pointer_group_interface__extract_elements (me, (Item*)0, "stems");
528 if (stems.size () < 1)
531 Grob *common = me->common_refpoint (stems[0], Y_AXIS);
532 for (int i=1; i < stems.size (); i++)
533 common = common->common_refpoint (stems[i], Y_AXIS);
535 for (int i=0; i < stems.size (); i++)
538 if (Stem::invisible_b (s))
541 Real stem_y = calc_stem_y_f (me, s, y, dy);
543 /* caution: stem measures in staff-positions */
544 Real id = me->relative_coordinate (common, Y_AXIS)
545 - stems[i]->relative_coordinate (common, Y_AXIS);
546 Stem::set_stemend (s, (stem_y + id) / half_space);
551 [Ross] (simplification of)
552 Set dy complying with:
554 - thick / 2 + staffline_f / 2
555 - thick + staffline_f
559 Beam::quantise_dy_f (Grob*me,Real dy)
563 SCM proc = me->get_grob_property ("height-quants");
564 SCM quants = gh_call2 (proc, me->self_scm (),
565 gh_double2scm (me->paper_l ()->get_var ("stafflinethickness")
569 for (SCM s = quants; gh_pair_p (s); s = gh_cdr (s))
570 a.push (gh_scm2double (gh_car (s)));
575 Real staff_space = Staff_symbol_referencer::staff_space (me);
577 Interval iv = quantise_iv (a, abs (dy)/staff_space) * staff_space;
578 Real q = (abs (dy) - iv[SMALLER] <= iv[BIGGER] - abs (dy))
582 return q * sign (dy);
586 Prevent interference from stafflines and beams.
587 See Documentation/tex/fonts.doc
589 We only need to quantise the (left) y-position of the beam,
590 since dy is quantised too.
591 if extend_b then stems must *not* get shorter
594 Beam::quantise_y_f (Grob*me,Real y, Real dy, int quant_dir)
596 int multiplicity = get_multiplicity (me);
598 Real staff_space = Staff_symbol_referencer::staff_space (me);
599 Real thick = me->paper_l ()->get_var ("stafflinethickness");
602 SCM proc = me->get_grob_property ("vertical-position-quant-function");
603 SCM quants = scm_apply (proc,
605 gh_list (gh_int2scm (multiplicity),
606 gh_double2scm (dy/staff_space),
607 gh_double2scm (thick/staff_space),
608 SCM_EOL, SCM_UNDEFINED));
612 for (; gh_pair_p (quants); quants = gh_cdr (quants))
613 a.push (gh_scm2double (gh_car (quants)));
618 Real up_y = Directional_element_interface::get (me) * y;
619 Interval iv = quantise_iv (a, up_y/staff_space) * staff_space;
621 Real q = up_y - iv[SMALLER] <= iv[BIGGER] - up_y
622 ? iv[SMALLER] : iv[BIGGER];
624 q = iv[(Direction)quant_dir];
626 return q * Directional_element_interface::get (me);
630 Beam::set_beaming (Grob*me,Beaming_info_list *beaming)
632 Link_array<Grob> stems=
633 Pointer_group_interface__extract_elements (me, (Grob*)0, "stems");
636 for (int i=0; i < stems.size(); i++)
640 /* Don't overwrite user override (?) */
641 if (Stem::beam_count (stems[i], d) == 0
642 /* Don't set beaming for outside of outer stems */
643 && ! (d == LEFT && i == 0)
644 && ! (d == RIGHT && i == stems.size () -1))
646 int b = beaming->infos_.elem (i).beams_i_drul_[d];
647 Stem::set_beaming (stems[i], b, d);
650 while (flip (&d) != LEFT);
657 beams to go with one stem.
662 Beam::stem_beams (Grob*me,Item *here, Item *next, Item *prev)
664 // ugh -> use commonx
665 if ((next && !(next->relative_coordinate (0, X_AXIS) > here->relative_coordinate (0, X_AXIS))) ||
666 (prev && !(prev->relative_coordinate (0, X_AXIS) < here->relative_coordinate (0, X_AXIS))))
667 programming_error ("Beams are not left-to-right");
669 Real staffline_f = me->paper_l ()->get_var ("stafflinethickness");
670 int multiplicity = get_multiplicity (me);
672 SCM space_proc = me->get_grob_property ("space-function");
673 SCM space = gh_call1 (space_proc, gh_int2scm (multiplicity));
675 Real thick = gh_scm2double (me->get_grob_property ("thickness")) ;
676 Real interbeam_f = gh_scm2double (space) ;
678 Real bdy = interbeam_f;
679 Real stemdx = staffline_f;
681 // ugh -> use commonx
682 Real dx = visible_stem_count (me) ?
683 last_visible_stem (me)->relative_coordinate (0, X_AXIS) - first_visible_stem (me)->relative_coordinate (0, X_AXIS)
685 Real dy = gh_scm2double (me->get_grob_property ("height"));
686 Real dydx = dy && dx ? dy/dx : 0;
692 if (!Stem::first_head (here))
695 int t = Stem::type_i (here);
697 SCM proc = me->get_grob_property ("flag-width-function");
698 SCM result = gh_call1 (proc, gh_int2scm (t));
699 nw_f = gh_scm2double (result);
703 Direction dir = Directional_element_interface::get (me);
705 /* half beams extending to the left. */
708 int lhalfs= lhalfs = Stem::beam_count (here,LEFT) - Stem::beam_count (prev,RIGHT);
709 int lwholebeams= Stem::beam_count (here,LEFT) <? Stem::beam_count (prev,RIGHT) ;
711 Half beam should be one note-width,
712 but let's make sure two half-beams never touch
714 Real w = here->relative_coordinate (0, X_AXIS) - prev->relative_coordinate (0, X_AXIS);
717 if (lhalfs) // generates warnings if not
718 a = Lookup::beam (dydx, w, thick);
719 a.translate (Offset (-w, -w * dydx));
720 for (int j = 0; j < lhalfs; j++)
723 b.translate_axis (-dir * bdy * (lwholebeams+j), Y_AXIS);
724 leftbeams.add_molecule (b);
730 int rhalfs = Stem::beam_count (here,RIGHT) - Stem::beam_count (next,LEFT);
731 int rwholebeams= Stem::beam_count (here,RIGHT) <? Stem::beam_count (next,LEFT) ;
733 Real w = next->relative_coordinate (0, X_AXIS) - here->relative_coordinate (0, X_AXIS);
734 Molecule a = Lookup::beam (dydx, w + stemdx, thick);
735 a.translate_axis( - stemdx/2, X_AXIS);
739 SCM gap = me->get_grob_property ("gap");
740 if (gh_number_p (gap))
742 int gap_i = gh_scm2int ( (gap));
743 int nogap = rwholebeams - gap_i;
745 for (; j < nogap; j++)
748 b.translate_axis (-dir * bdy * j, Y_AXIS);
749 rightbeams.add_molecule (b);
751 // TODO: notehead widths differ for different types
754 a = Lookup::beam (dydx, w + stemdx, thick);
757 for (; j < rwholebeams; j++)
760 b.translate (Offset (Stem::invisible_b (here) ? 0 : gap_f, -dir * bdy * j));
761 rightbeams.add_molecule (b);
766 a = Lookup::beam (dydx, w, thick);
768 for (; j < rwholebeams + rhalfs; j++)
771 b.translate_axis (- dir * bdy * j, Y_AXIS);
772 rightbeams.add_molecule (b);
776 leftbeams.add_molecule (rightbeams);
779 Does beam quanting think of the asymetry of beams?
780 Refpoint is on bottom of symbol. (FIXTHAT) --hwn.
786 TODO: it would be nice to introduce y-position via callbacks.
789 MAKE_SCHEME_CALLBACK(Beam,brew_molecule,1);
791 Beam::brew_molecule (SCM smob)
793 Grob * me =unsmob_grob (smob);
796 if (!gh_pair_p (me->get_grob_property ("stems")))
799 Link_array<Item>stems =
800 Pointer_group_interface__extract_elements (me, (Item*) 0, "stems");
801 if (visible_stem_count (me))
803 // ugh -> use commonx
804 x0 = first_visible_stem (me)->relative_coordinate (0, X_AXIS);
805 dx = last_visible_stem (me)->relative_coordinate (0, X_AXIS) - x0;
809 x0 = stems[0]->relative_coordinate (0, X_AXIS);
810 dx = stems.top()->relative_coordinate (0, X_AXIS) - x0;
814 Real dy = gh_scm2double (me->get_grob_property ("height"));
815 Real dydx = dy && dx ? dy/dx : 0;
816 Real y = gh_scm2double (me->get_grob_property ("y-position"));
819 for (int j=0; j <stems.size (); j++)
822 Item * prev = (j > 0)? stems[j-1] : 0;
823 Item * next = (j < stems.size()-1) ? stems[j+1] :0;
825 Molecule sb = stem_beams (me, i, next, prev);
826 Real x = i->relative_coordinate (0, X_AXIS)-x0;
827 sb.translate (Offset (x, x * dydx + y));
828 mol.add_molecule (sb);
830 mol.translate_axis (x0
831 - dynamic_cast<Spanner*> (me)->get_bound (LEFT)->relative_coordinate (0, X_AXIS), X_AXIS);
833 return mol.smobbed_copy ();
837 Beam::forced_stem_count (Grob*me)
839 Link_array<Item>stems =
840 Pointer_group_interface__extract_elements ( me, (Item*) 0, "stems");
842 for (int i=0; i < stems.size (); i++)
846 if (Stem::invisible_b (s))
849 if (((int)Stem::chord_start_f (s))
850 && (Stem::get_direction (s ) != Stem::get_default_dir (s )))
860 use filter and standard list functions.
863 Beam::visible_stem_count (Grob*me)
865 Link_array<Item>stems =
866 Pointer_group_interface__extract_elements (me, (Item*) 0, "stems");
868 for (int i = stems.size (); i--;)
870 if (!Stem::invisible_b (stems[i]))
877 Beam::first_visible_stem(Grob*me)
879 Link_array<Item>stems =
880 Pointer_group_interface__extract_elements ( me, (Item*) 0, "stems");
882 for (int i = 0; i < stems.size (); i++)
884 if (!Stem::invisible_b (stems[i]))
891 Beam::last_visible_stem(Grob*me)
893 Link_array<Item>stems =
894 Pointer_group_interface__extract_elements ( me, (Item*) 0, "stems");
895 for (int i = stems.size (); i--;)
897 if (!Stem::invisible_b (stems[i]))
906 handle rest under beam (do_post: beams are calculated now)
907 what about combination of collisions and rest under beam.
911 rest -> stem -> beam -> interpolate_y_position ()
913 MAKE_SCHEME_CALLBACK(Beam,rest_collision_callback,2);
915 Beam::rest_collision_callback (SCM element_smob, SCM axis)
917 Grob *rest = unsmob_grob (element_smob);
918 Axis a = (Axis) gh_scm2int (axis);
920 assert (a == Y_AXIS);
922 Grob * st = unsmob_grob (rest->get_grob_property ("stem"));
925 return gh_double2scm (0.0);
926 Grob * beam = unsmob_grob (stem->get_grob_property ("beam"));
927 if (!beam || !Beam::has_interface (beam) || !Beam::visible_stem_count (beam))
928 return gh_double2scm (0.0);
930 // make callback for rest from this.
935 // todo: make sure this calced already.
936 SCM s = beam->get_grob_property ("height");
938 beam_dy = gh_scm2double (s);
940 s = beam->get_grob_property ("y-position");
942 beam_y = gh_scm2double (s);
944 // ugh -> use commonx
945 Real x0 = first_visible_stem(beam)->relative_coordinate (0, X_AXIS);
946 Real dx = last_visible_stem(beam)->relative_coordinate (0, X_AXIS) - x0;
947 Real dydx = beam_dy && dx ? beam_dy/dx : 0;
949 Direction d = Stem::get_direction (stem);
950 Real beamy = (stem->relative_coordinate (0, X_AXIS) - x0) * dydx + beam_y;
952 Real staff_space = Staff_symbol_referencer::staff_space (rest);
955 Real rest_dim = rest->extent (rest, Y_AXIS)[d]*2.0 / staff_space ; // refp??
958 = gh_scm2double (rest->get_grob_property ("minimum-beam-collision-distance"));
960 minimum_dist + -d * (beamy - rest_dim) >? 0;
962 int stafflines = Staff_symbol_referencer::line_count (rest);
964 // move discretely by half spaces.
965 int discrete_dist = int (ceil (dist));
967 // move by whole spaces inside the staff.
968 if (discrete_dist < stafflines+1)
969 discrete_dist = int (ceil (discrete_dist / 2.0)* 2.0);
971 return gh_double2scm (-d * discrete_dist);
976 Beam::has_interface (Grob*me)
978 return me->has_interface (ly_symbol2scm ("beam-interface"));
982 Beam::set_interface (Grob*me)
985 why the init? No way to tell difference between default and user
987 me->set_grob_property ("height", gh_int2scm (0)); // ugh.
988 me->set_grob_property ("y-position" ,gh_int2scm (0));
989 me->set_interface (ly_symbol2scm("beam-interface"));